1. Field of the Invention
The present invention relates to an intrusion detection device for detecting an unauthorized object such as, for example, a human body illegally intruding into a predetermined warning area.
2. Description of Related Art
It is well known that the standard intrusion detecting device of the kind referred to above generally employs a main unit including a detecting element, which main unit is so designed and so configured as to make use of either a passive infrared ray (PIR) detection system or an active infrared ray (AIR) detection system.
Also, in recent years, the intrusion detecting device has been suggested, in which a wireless system is employed to enable an intrusion detection signal to be transmitted from a wireless transmitter to a wireless receiver of a control device to thereby eliminate the need to use any wiring between the control device and the transmitter. In this type of the intrusion detecting device, a commercially available transmitter is employed for the wireless transmitter and an electric driving power is occasionally supplied from a power source battery, built in the wireless transmitter, to the main unit. In such case, the capacity of the electric power needed in the intrusion detecting device as a whole depends on the battery built in the wireless transmitter employed. Also, in the event that wastage of the battery in the wireless transmitter is detected, a signal indicative of the power wastage is transmitted wireless to the receiver so that the latter can issue an audible and/or visible warning. It is to be noted that, regarding the battery used in this way, a battery storage casing has been suggested, which is of a design capable of accommodating batteries of various different sizes (such as disclosed in, for example, the Patent Document 1 listed below).